Ultraviolet (UV) radiation having wavelengths from about 280 to about 400 nm may cause the degradation of exposed organic matter such as plastics and will burn and/or induce tumors in human skin. To negate these undesirable actions, plastics and the like are protected by chemical additives called UV stabilizers and human skin and hair are protected by cosmetics containing UV stabilizers or sunscreens.
To be viable for commercial applications, a UV stabilizer should inhibit or dramatically retard degradation of organic material exposed to light by one or a combination of mechanisms such as the absorption of light energy or the entrapment of the destructive free radicals produced in the material by its interaction with light or oxygen or both. Absorbers should preferably have a strong ultraviolet light absorptivity at wave lengths between 280 and 400 nm. A light stabilizer should also be photostable by itself, be compatible with the substrate (e.g. plastic or cosmetic emulsion) in which it is used as an additive, be non-volatile at the high temperatures involved during incorporation and processing stages as well as during certain end uses, possess low color, be chemically inert, have low or no toxicity or skin sensitization/irritation properties, be non-mutagenic, and be stable to the environments experienced during its processing and application. Furthermore, for human sunscreen use, it is also desirable that the UV stabilizer be relatively insoluble in water.
Accordingly, it is an object of the present invention to provide a novel class of UV light stabilizer compounds.
A specific object of this invention is to provide a novel class of UV light stabilizer compounds which may be used to stabilize ultraviolet degradable organic compositions, particularly plastics such as polyethylene and polypropylene, against deterioration resulting from the exposure to such UV radiation.
Another specific object is to provide a novel class of UV light stabilizer compounds which might be used in human cosmetic products such as sunscreens, hair dyes and hair tinting compositions to prevent or retard UV radiation from penetrating the human skin or hair.
These and other objects and features of the invention will be made apparent from the following more particular description of the invention.